Connection oriented protocols use a calculated route for data communication on a given session between source and destination nodes until that route is no longer usable or the session is terminated. All connection oriented networks operate in generally the same way to calculate a route between a source node and a destination node and that route is used to transmit all packets on the session in question until the session ends. All connection oriented networks also use generally the same technique to calculate the session route. If the source node does not know the destination node or the destination application, initially, when a session is to be setup, the source node broadcasts a locate inquiry packet into the network to locate the destination node or the node containing the desired application. As the inquiry packet propagates through the network, the route used in reaching its present location is inserted into the header of the packet. Eventually, when the destination node or application is reached, the route used to get there is in the packet header and a reply packet containing that route is transmitted back through the network to the source node using the reverse of the route that was used in getting to the destination node. When the source node receives the reply packet, it knows from the packet header the calculated route to the destination node. From this point, a number of variations are used in transmitting data packets to the destination node. However, in every case, the calculated route is used for all packets until the session is ended.
A problem arises in such networks when the route between source and destination nodes includes nodes in separate networks. For purposes here, separate networks are characterized by the fact that each network knows nothing about the topology of the other networks, other than the links that exist between border nodes of the networks. This fact leads to the calculation of routes that may be suboptimal in the sense that a calculated route may contain unnecessary hops between nodes of separate networks.